This invention relates to a method for the machining of a workpiece and, more particularly, to a method for operating a numerically controlled lathe to accomplish three dimensional workpiece contouring.
Typically, numerically controlled mills have been used in the machining of workpieces which require contouring in three dimensions. The milling tool, under computer control, produces cuts in the workpiece which define the desired three dimensional contouring.
A problem with the numerically controlled milling process is that it is relatively labor intensive. The milling of a part often requires manual intervention to reposition the part on the bed of the mill. Such repositioning is often critical to successful part fabrication and, as such, requires a significant amount of time by a skilled operator.
In addition, a mill produced part often requires substantial handwork, such as filing, to produce a finished part.
A numerically controlled lathe provides a much faster way of machining workpieces. Here, a workpiece is mounted to a rotating spindle. A cutting tool may be positioned with respect to the radial and axial axes of the workpiece under computer control. Thus, as the workpiece rotates, the cutting tool moves both axially and radially to cut the desired shape. Inasmuch as the workpiece need be positioned only once by an operator, the lathe process is substantially less labor intensive than is the milling process.
A drawback to the lathe process is, however, that heretofore it has only been useful for two dimensional contouring of a part. Prior attempts at adapting a numerically controlled lathe for three dimensional contouring have failed due to the complexities involved in reducing design information into suitable lathe control signals and to the volume of control signals which would be required to realize three dimensional lathe contouring.